IN its 20-year history the special unit at Barlinnie Prison in Glasgow faced public hostility and was derided as a soft option for some of the country’s most violent and uncontrollable men.

But many rated it a success as infamous prisoners, such murderers Jimmy Boyle and Hugh Collins, emerged as respected artists
and writers.

Now a leading criminologist is advocating its return and reckons it would be a suitable set-up to treat the likes of Aaron Campbell, the schoolboy who abducted, raped and murdered six-year-old Alesha MacPhail on Bute, in Argyll last year.

Professor David Wilson believes the special unit would be the best way to protect society from the teenage killer, who is appealing against his 27-year minimum sentence. 

“Campbell was described as a psychopath in court and was completely unrepentant. How do you go about treating that kind of offender? The Scottish Prison Service hasn’t worked that out, but if they brought back the Barlinnie special unit they could treat him,” said Mr Wilson.

“Aaron Campbell will be released at some date and I’d rather he came out after being treated.”

Campbell, who is now 17, will be eligible for parole in 2045, when he is 43.

The teenager denied killing Alesha during his trial but later admitted the horrific crime to a criminal psychologist preparing a pre-sentencing background report.

He told the psychologist he was “mildly amused” police took two days to arrest him after Alesha’s body was found and that he had to “zip his mouth” to stop himself laughing during the trial. 

Sentencing, Lord Matthews described him as a “cold, callous, calculating, remorseless and dangerous individual” – the kind of offender Mr Wilson has spent 40 years studying and has chronicled in his book, My Life with Murderers.

Mr Wilson will be appearing at literary crime festival Bloody Scotland next month to talk about his career as a prison governor and criminologist and meeting some of the world’s most dangerous men, including serial killer Dennis Nilsen.

At 29 he became the UK’s youngest ever prison governor, working at Wormwood Scrubs, Grendon and Woodhill, where he helped design units to rehabilitate the most violent prisoners in the country.

Mr Wilson believes the Barlinnie special unit, which had similar aims, was shut down in 1993 for political reasons to appease public outrage.

“Penal reform has gone from nothing works to something works, to this works but can’t be seen to work. I’m interested in keeping society safe. I don’t want tough justice or soft justice, I want smart justice.”

Despite being an advocate for rehabilitation and prison reform, Mr Wilson does not believe  all criminals can be put back into society. “In some cases, they are too dangerous, and in others, they may not present a danger but their crime is so heinous it would be wrong to release them.”

In his book, Mr Wilson, a Scot, describes meeting Nilsen, who was convicted of six murders in 1983 and died in prison last May. 

“When I met Nilsen, he tried to dominate the interview, as many psychopaths like to control a situation. Afterwards he sent me 600 pages of letters, all nonsense, trying to justify his actions. Most psychopathic killers refuse to talk, so this was unusual. I was in my 20s when I met him – I think he just fancied me.” 

Mr Wilson is under no delusion the men he has interviewed over the years – one of whom he counts as his friend and whose wedding he attended – are dangerous.

When he meets them he makes sure his chair is near the door and that he is in the sightline of a prison guard at all times.

“Usually I can tell if someone is about to attack me by their body language, but the most terrifying ones are those who go from zero to 100 in the blink of an eye.”

He has developed his own technique to try to get at the truth with psychopaths, who can be accomplished liars.

“I detach myself from their crimes and set up a rapport to get them to open up, then I ask them questions that seem to come out of left field, which can unnerve them so they slip up.”

Mr Wilson, whose Crime Files is now on the BBC Scotland channel, has met enough murderers to know the stereotype of the serial killer as seen on dramas such as Mindhunter is just that – a stereotype.

“People imagine violent and lethal men are monstrous, alien, but what I have learned is how seemingly ordinary men can do dreadful things, often in the most banal of places for the most ludicrous of reasons.”  

My Life with Murderers, Sphere, £20. Professor Wilson will be at the Bloody Scotland International Crime Writing Festival in Stirling on  September 21.